Porphyromonas gingivalis polypeptides and nucleotides

ABSTRACT

The present invention relates to isolated  Porphyromonas gingivalis  polypeptides and nucleotides. The polypeptides include an amino acid sequence selected from the group consisting of: SEQ. ID. NO. 110; SEQ. ID. NO. 111; SEQ. ID. NO. 112; SEQ. ID. NO. 113; SEQ ID NO: 120; SEQ. ID. NO. 123; SEQ. ID. NO. 124; SEQ. ID. NO. 125; SEQ. ID. NO. 130; SEQ. ID. NO. 131; SEQ. ID. NO. 132; SEQ. ID. NO. 133; SEQ. ID. NO. 135; SEQ. ID. NO. 136; SEQ. ID. NO. 137; SEQ. ID. NO. 138; SEQ. ID. NO. 143; SEQ. ID. NO. 144; SEQ. ID. NO. 145; SEQ. ID. NO. 146; SEQ. ID. NO. 147; SEQ. ID. NO. 148; and amino acid sequences at least 95% identical thereto.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 12/382,845, filed on Mar. 25, 2009, which is a continuation of U.S. patent application Ser. No. 11/589,261, filed Oct. 30, 2006, which is a continuation of U.S. patent application Ser. No. 09/581,286, filed Jun. 28, 2000, which is a U.S. national stage of PCT/AU98/01023, filed Dec. 10, 1998, the entire contents of each of these applications is incorporated herein by reference. In particular, the entire contents of application Ser. No. 11/589,261, now U.S. Pat. No. 7,544,777, issued on Jun. 9, 2009, is incorporated herein by reference, including specifically the sequence numbers: SEQ. ID. NO. 1 to SEQ ID NO: 721.

FIELD OF THE INVENTION

The present invention relates to Porphyromonas gingivalis nucleotide sequences, P. gingivalis polypeptides and probes for detection of P. gingivalis. The P. gingivalis polypeptides and nucleotides can be used in compositions for use in raising an immune response in a subject against P. gingivalis and treating or preventing or reducing the severity of the condition known as periodontitis.

BACKGROUND OF THE INVENTION

Periodontal diseases are bacterial-associated inflammatory diseases of the supporting tissues of the teeth and range from the relatively mild form of gingivitis, the non-specific, reversible inflammation of gingival tissue to the more aggressive forms of periodontitis which are characterised by the destruction of the tooth's supporting structures. Periodontitis is associated with a subgingival infection of a consortium of specific Gram-negative bacteria that leads to the destruction of the periodontium and is a major public health problem. One bacterium that has attracted considerable interest is P. gingivalis as the recovery of this microorganism from adult periodontitis lesions can be up to 50% of the subgingival anaerobically cultivable flora, whereas P. gingivalis is rarely recovered, and then in low numbers, from healthy sites. A proportional increase in the level of P. gingivalis in subgingival plaque has been associated with an increased severity of periodontitis and eradication of the microorganism from the cultivable subgingival microbial population is accompanied by resolution of the disease. The progression of periodontitis lesions in non-human primates has been demonstrated with the subgingival implantation of P. gingivalis. These findings in both animals and humans suggest a major role for P. gingivalis in the development of adult periodontitis.

P. gingivalis is a black-pigmented, anaerobic, asaccharolytic, proteolytic Gram-negative rod that obtains energy from the metabolism of specific amino acids. The microorganism has an absolute growth requirement for iron, preferentially in the form of haeme or its Fe(III) oxidation product haemin and when grown under conditions of excess haemin is highly virulent in experimental animals. A number of virulence factors have been implicated in the pathogenicity of P. gingivalis including the capsule, adhesins, cytotoxins and extracellular hydrolytic enzymes.

In order to develop an efficacious and safe vaccine to prevent, eliminate or reduce P. gingivalis colonisation it is necessary to identify and produce antigens that are involved in virulence that have utility as immunogens possibly through the generation of specific antibodies. Whilst it is possible to attempt to isolate antigens directly from cultures of P. gingivalis this is often difficult. For example as mentioned above, P. gingivalis is a strict anaerobe and can be difficult to isolate and grow. It is also known that, for a number of organisms, when cultured in vitro that many virulence genes are down regulated and the encoded proteins are no longer expressed. If conventional chemistry techniques were applied to purify vaccine candidates potentially important (protective) molecules may not be identified. With DNA sequencing, as the gene is present (but not transcribed) even when the organism is grown in vitro it can be identified, cloned and produced as a recombinant DNA protein. Similarly, a protective antigen or therapeutic target may be transiently expressed by the organism in vitro or produced in low levels making the identification of these molecules extremely difficult by conventional methods.

With serological identification of therapeutic targets one is limited to those responses which are detectable using standard methods such as Western Blotting or ELISA. The limitation here is the both the level of response that is generated by the animal or human and determining whether this response is protective, damaging or irrelevant. No such limitation is present with a sequencing approach to the identification of potential therapeutic or prophylactic targets.

It is also well known that P. gingivalis produces a range of broadly active proteases (University of Melbourne International Patent Application No PCT/AU 96/00673, U.S. Pat. Nos. 5,475,097 and 5,523,390), which make the identification of intact proteins difficult because of their degradation by these proteases.

SUMMARY OF THE INVENTION

The present inventors have attempted to isolate P. gingivalis nucleotide sequences which can be used for recombinant production of P. gingivalis polypeptides and to develop nucleotide probes specific for P. gingivalis. The DNA sequences listed below have been selected from a large number of P. gingivalis sequences according to their indicative potential as vaccine candidates. This intuitive step involved comparison of the deduced protein sequence from the P. gingivalis DNA sequences to the known protein sequence databases. Some of the characteristics used to select useful vaccine candidates include; the expected cellular location, such as outer membrane proteins or secreted proteins, particular functional activities of similar proteins such as those with an enzymatic or proteolytic activity, proteins involved in essential metabolic pathways that when inactivated or blocked may be deleterious or lethal to the organism, proteins that might be expected to play a role in the pathogenesis of the organism eg. red cell lysis, cell agglutination or cell receptors and proteins which are paralogues to proteins with proven vaccine efficacy.

In a first aspect the present invention consists of an isolated antigenic Porphyromonas gingivalis polypeptide or an antigenic fragment thereof, the polypeptide comprising an amino acid sequence selected from the group consisting of: SEQ. ID. NO. 110; SEQ. ID. NO. 111; SEQ. ID. NO. 112; SEQ. ID. NO. 113; SEQ ID NO: 120; SEQ. ID. NO. 123; SEQ. ID. NO. 124; SEQ. ID. NO. 125; SEQ. ID. NO. 130; SEQ. ID. NO. 131; SEQ. ID. NO. 132; SEQ. ID. NO. 133; SEQ. ID. NO. 135; SEQ. ID. NO. 136; SEQ. ID. NO. 137; SEQ. ID. NO. 138; SEQ. ID. NO. 143; SEQ. ID. NO. 144; SEQ. ID. NO. 145; SEQ. ID. NO. 146; SEQ. ID. NO. 147; and SEQ. ID. NO. 148;

or amino acid sequences at least 95% identical to an amino acid sequence selected from the group consisting of: SEQ. ID. NO. 110; SEQ. ID. NO. 111; SEQ. ID. NO. 112; SEQ. ID. NO. 113; SEQ ID NO: 120; SEQ. ID. NO. 123; SEQ. ID. NO. 124; SEQ. ID. NO. 125; SEQ. ID. NO. 130; SEQ. ID. NO. 131; SEQ. ID. NO. 132; SEQ. ID. NO. 133; SEQ. ID. NO. 135; SEQ. ID. NO. 136; SEQ. ID. NO. 137; SEQ. ID. NO. 138; SEQ. ID. NO. 143; SEQ. ID. NO. 144; SEQ. ID. NO. 145; SEQ. ID. NO. 146; SEQ. ID. NO. 147; and SEQ. ID. NO. 148;

or an amino acid sequence of at least 40 amino acids having a contiguous sequence of at least 40 amino acids identical to a contiguous amino acid sequence selected from the group consisting of: SEQ. ID. NO. 110; SEQ. ID. NO. 111; SEQ. ID. NO. 112; SEQ. ID. NO. 113; SEQ ID NO: 120; SEQ. ID. NO. 123; SEQ. ID. NO. 124; SEQ. ID. NO. 125; SEQ. ID. NO. 130; SEQ. ID. NO. 131; SEQ. ID. NO. 132; SEQ. ID. NO. 133; SEQ. ID. NO. 135; SEQ. ID. NO. 136; SEQ. ID. NO. 137; SEQ. ID. NO. 138; SEQ. ID. NO. 143; SEQ. ID. NO. 144; SEQ. ID. NO. 145; SEQ. ID. NO. 146; SEQ. ID. NO. 147; and SEQ. ID. NO. 148.

As used herein % identity for polypeptides is to be calculated using the alignment algorithm of Needleman and Munsch (9) using a standard protein scoring matrix (Blosum 50).

In a preferred embodiment the present invention provides a polypeptide or fragment thereof, the polypeptide comprising an amino acid sequence selected from the group consisting of: SEQ. ID. NO. 110; SEQ. ID. NO. 111; SEQ. ID. NO. 112; SEQ. ID. NO. 113; SEQ ID NO: 120; SEQ. ID. NO. 123; SEQ. ID. NO. 124; SEQ. ID. NO. 125; SEQ. ID. NO. 130; SEQ. ID. NO. 131; SEQ. ID. NO. 132; SEQ. ID. NO. 133; SEQ. ID. NO. 135; SEQ. ID. NO. 136; SEQ. ID. NO. 137; SEQ. ID. NO, 138; SEQ. ID. NO, 143; SEQ. ID. NO. 144; SEQ. ID. NO. 145; SEQ. ID. NO. 146; SEQ. ID. NO. 147; and SEQ. ID. NO. 148.

In a second aspect the present invention consists in an isolated DNA molecule, the DNA molecule comprising a nucleotide sequence which encodes the polypeptide of the first aspect of the present invention or a sequence which hybridises thereto under stringent conditions.

It is preferred that the isolated DNA molecule comprises a nucleotide sequence selected from the group consisting of SEQ ID NO: 36 to SEQ ID NO: 39; SEQ ID NO: 46; SEQ ID NO: 49 to SEQ ID NO: 51; SEQ ID NO: 56 to SEQ ID NO: 59; SEQ ID NO: 61 to SEQ ID NO:64; SEQ ID NO: 69 to SEQ ID NO: 74; SEQ ID NO: 3 to SEQ ID NO: 5; SEQ ID NO: 11; SEQ ID NO: 14 to SEQ ID NO: 16; SEQ ID NO: 21; SEQ ID NO: 22; SEQ ID NO: 24 to SEQ ID NO: 26; SEQ ID NO: 28 to SEQ ID NO: 33.

In a third aspect the present invention consists in a recombinant expression vector comprising the DNA molecule of the second aspect of the present invention operably linked to a transcription regulatory element.

The present invention also provides a cell comprising this recombinant expression vector.

In a further aspect the present invention consists in a method for producing a P. gingivalis polypeptide comprising culturing the cell under conditions that permit expression of the polypeptide.

In yet a further aspect the present invention provides a composition for use in raising an immune response directed against P. gingivalis in a subject, the composition comprising an effective amount of at least one polypeptide of the first aspect of the present invention, or at least one DNA molecule of the second aspect of the present invention, or both, and a pharmaceutically acceptable carrier. It is preferred that the pharmaceutically acceptable carrier is an adjuvant. In other aspects the present invention provides methods of treating P. gingivalis infection in subject comprising the administration of the composition to the subject such that treatment of P. gingivalis infection occurs. The treatment may be prophylactic or therapeutic.

In yet another aspect the present invention provides an antibody raised against a polypeptide of the first aspect the invention. The antibody may be polyclonal or monoclonal. The present invention also provides compositions including these antibodies. It is preferred that these compositions are adapted for oral use and may be, for example, dentrifices, mouthwashes, etc.

In a still further aspect the present invention provides a nucleotide probe comprising at least 18 nucleotides and having a contiguous sequence of at least 18 nucleotides identical to a contiguous nucleotide sequence selected from the group consisting of SEQ ID NO: 3 to SEQ ID NO: 5; SEQ ID NO: 11; SEQ ID NO: 14 to SEQ ID NO: 16; SEQ ID NO: 21; SEQ ID NO: 22; SEQ ID NO: 24 to SEQ ID NO: 26; SEQ ID NO: 28 to SEQ ID NO: 33; and sequences complementary thereto. It is preferred that the probe further comprises a detectable label.

The present invention also provides a method for detecting the presence of P. gingivalis nucleic acid in a sample comprising:

-   -   (a) contacting a sample with the nucleotide probe under         conditions in which a hybrid can form between the probe and a P.         gingivalis nucleic acid in the sample; and     -   (b) detecting the hybrid formed in step (a), wherein detection         of a hybrid indicates the presence of a P. gingivalis nucleic         acid in the sample.

DETAILED DESCRIPTION Definitions

A purified or isolated polypeptide or a substantially pure preparation of a polypeptide are used interchangeably herein and, as used herein, mean a polypeptide that has been separated from other proteins, lipids, and nucleic acids with which it naturally occurs. Preferably, the polypeptide is also separated from substances, e.g., antibodies or gel matrix, e.g., polyacrylamide, which are used to purify it. Preferably, the polypeptide constitutes at least 10, 20, 50 70, 80 or 95% dry weight of the purified preparation. Preferably, the preparation contains: sufficient polypeptide to allow protein sequencing; at least 1, 10, or 100 mg of the polypeptide.

A purified preparation of cells refers to, in the case of plant or animal cells, an in vitro preparation of cells and not an entire intact plant or animal. In the case of cultured cells or microbial cells, it consists of a preparation of at least 10% and more preferably 50% of the subject cells.

A purified or isolated or a substantially pure nucleic acid, e.g., a substantially pure DNA, (are terms used interchangeably herein) is a nucleic acid which is one or both of the following: not immediately contiguous with both of the coding sequences with which it is immediately contiguous (i.e., one at the 5′ end and one at the 3′ end) in the naturally occurring genome of the organism from which the nucleic acid is derived; or which is substantially free of a nucleic acid with which it occurs in the organism from which the nucleic acid is derived. The term includes, for example, a recombinant DNA which is incorporated into a vector, e.g., into an autonomously replicating plasmid or virus, or into the genomic DNA of a prokaryote or eukaryote, or which exists as a separate molecule (e.g., a cDNA or a genomic DNA fragment produced by PCR or restriction endonuclease treatment) independent of other DNA sequences. Substantially pure DNA also includes a recombinant DNA which is part of a hybrid gene encoding additional P. gingivalis DNA sequence.

A “contig” as used herein is a nucleic acid representing a continuous stretch of genomic sequence of an organism.

An “open reading frame”, also referred to herein as ORF, is a region of nucleic acid which encodes a polypeptide. This region may represent a portion of a coding sequence or a total sequence and can be determined from a stop to stop codon or from a start to stop codon.

As used herein, a “coding sequence” is a nucleic acid which is transcribed into messenger RNA and/or translated into a polypeptide when placed under the control of appropriate regulatory sequences. The boundaries of the coding sequence are determined by a translation start codon at the five prime terminus and a translation stop code at the three prime terminus. A coding sequence can include but is not limited to messenger RNA synthetic DNA, and recombinant nucleic acid sequences.

A “complement” of a nucleic acid as used herein refers to an anti-parallel or antisense sequence that participates in Watson-Crick base-pairing with the original sequence.

A “gene product” is a protein or structural RNA which is specifically encoded by a gene.

As used herein, the term “probe” refers to a nucleic acid, peptide or other chemical entity which specifically binds to a molecule of interest. Probes are often associated with or capable of associating with a label. A label is a chemical moiety capable of detection. Typical labels comprise dyes, radioisotopes, luminescent and chemiluminescent moieties, fluorophores, enzymes, precipitating agents, amplification sequences, and the like. Similarly, a nucleic acid, peptide or other chemical entity which specifically binds to a molecule of interest and immobilizes such molecule is referred herein as a “capture ligand”. Capture ligands are typically associated with or capable of associating with a support such as nitro-cellulose, glass, nylon membranes, beads, particles and the like. The specificity of hybridization is dependent on conditions such as the base pair composition of the nucleotides, and the temperature and salt concentration of the reaction. These conditions are readily discernible to one of ordinary skill in the art using routine experimentation.

Homologous refers to the sequence similarity or sequence identity between two polypeptides or between two nucleic acid molecules. When a position in both of the two compared sequences is occupied by the same base or amino acid monomer subunit, e.g., if a position in each of two DNA molecules is occupied by adenine, then the molecules are homologous at that position. The percent of homology between two sequences is a function of the number of matching or homologous positions shared by the two sequences divided by the number of positions compared×100.

The terms peptides, proteins, and polypeptides are used interchangeably herein.

An “immunogenic component” as used herein is a moiety, such as an P. gingivalis polypeptide, analog or fragment thereof, that is capable of eliciting a humoral and/or cellular immune response in a host animal.

An “antigenic component” as used herein is a moiety, such as P. gingivalis polypeptide, analog or fragment thereof, that is capable of binding to a specific antibody with sufficiently high affinity to form a detectable antigen-antibody complex.

As used herein, the term “cell-specific promoter” means a DNA sequence that serves as a promoter, i.e., regulates expression of a selected DNA sequence operably linked to the promoter, and which effects expression of the selected DNA sequence in specific cells of a tissue. The term also covers so-called “leaky” promoters, which regulate expression of a selected DNA primarily in one tissue, but cause expression in other tissues as well.

As used herein, the term “control sequence” refers to a nucleic acid having a base sequence which is recognized by the host organism to effect the expression of encoded sequences to which they are ligated. The nature of such control sequences differs depending upon the host organism; in prokaryotes, such control sequences generally include a promoter, ribosomal binding site, terminators, and in some cases operators; in eukaryotes, generally such control sequences include promoters, terminators and in some instances, enhancers. The term control sequence is intended to include at a minimum, all components whose presence is necessary for expression, and may also include additional components whose presence is advantageous, for example, leader sequences.

As used herein, the term “operably linked” refers to sequences joined or ligated to function in their intended manner. For example, a control sequence is operably linked to coding sequence by ligation in such a way that expression of the coding sequence is achieved under conditions compatible with the control sequence and host cell.

A “sample” as used herein refers to a biological sample, such as, for example, tissue or fluid isolated from an individual (including without limitation plasma. serum, cerebrospinal fluid, lymph, tears, saliva and tissue sections) or from in vitro cell culture constituents, as well as samples from the environment.

The practice of the invention will employ, unless otherwise indicated, conventional techniques of chemistry, molecular biology, microbiology, recombinant DNA, and immunology well known to those skilled in the art. Such techniques are described and explained throughout the literature in sources such as, J. Perbal, A Practical Guide to Molecular Cloning, John Wiley and Sons (1984), J. Sambrook et al., Molecular Cloning: A Laboratory Manual, Cold Spring Harbour Laboratory Press (1989), T. A. Brown (editor), Essential Molecular Biology: A Practical Approach, Volumes 1 and 2, IRL Press (1991), D. M. Glover and B. D. Hames (editors), DNA Cloning: A Practical Approach, Volumes 1-4, IRL Press (1995 and 1996), and F. M. Ausubel et al. (Editors), Current Protocols in Molecular Biology, Greene Pub. Associates and Wiley-Interscience (1988, including all updates until present). The disclosure of these texts are incorporated herein by reference.

Pharmaceutically Acceptable Carriers

The antibodies, polypeptides and DNA of the present invention can be included in compositions which include a carrier or diluent. These compositions include pharmaceutical compositions where the carrier or diluent will be pharmaceutically acceptable. Pharmaceutically acceptable carriers or diluents include those used in compositions suitable for oral, rectal, nasal, topical (including buccal and sublingual), vaginal, parenteral (including subcutaneous, intramuscular, intravenous, intradermal, intrathecal and epidural) administration. They are non-toxic to recipients at the dosages and concentrations employed. Representative examples of pharmaceutically acceptable carriers or diluents include, but are not limited to; water, isotonic solutions which are preferably buffered at a physiological pH (such as phosphate-buffered saline or Tris-buffered saline) and can also contain one or more of, mannitol, lactose, trehalose, dextrose, glycerol, ethanol or polypeptides (such as human serum albumin). The compositions may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy.

As will be well understood by those skilled in the art alterations may be made to the amino acid sequences set out in the Sequence Listings. These alterations may be deletions, insertions, or substitutions of amino acid residues. The altered polypeptides can be either naturally occurring (that is to say, purified or isolated from a natural source) or synthetic (for example, by performing site-directed metagenesis on the encoding DNA). It is intended that such altered polypeptides which have at least 85%, preferably at least 95% identity with the sequences set out in the Sequence Listing are within the scope of the present invention. Antibodies raised against these altered polypeptides will also bind to the polypeptides having one of the sequences set out in the Sequence Listings. The level of % identity is to be calculated as set out above.

Protein sequences are homologous if they are related by divergence from a common ancestor. Consequently, a species homologue of the protein will be the equivalent protein which occurs naturally in another species. Within any one species a homologue may exist as numerous allelic variants, and these will be considered homologues of the protein. Allelic variants and species homologues can be obtained by following standard techniques known to those skilled in the art.

An allelic variant will be a variant that is naturally occurring within an individual organism.

Mutants, Variants and Homology—Nucleic Acids

Mutant polynucleotides will possess one or more mutations which are deletions, insertions, or substitutions of nucleotide residues. Mutants can be either naturally occurring (that is to say, isolated from a natural source) or synthetic (for example, by performing site-directed metagenesis on the DNA). It is thus apparent that polynucleotides of the invention can be either naturally occurring or recombinant (that is to say prepared using recombinant DNA techniques).

An allelic variant will be a variant that is naturally occurring within an individual organism.

Nucleotide sequences are homologous if they are related by divergence from a common ancestor. Consequently, a species homologue of the polynucleotide will be the equivalent polynucleotide which occurs naturally in another species. Within any one species a homologue may exist as numerous allelic variants, and these will be considered homologues of the polynucleotide. Allelic variants and species homologues can be obtained by following standard techniques known to those skilled in the art.

Antibody Production

Antibodies, either polyclonal or monoclonal, which are specific for a polypeptide of the present invention can be produced by a person skilled in the art using standard techniques such as, but not limited to, those described by Harlow et al. Antibodies: A Laboratory Manual, Cold Springs Harbor Laboratory Press (1988), and D. Catty (editor), Antibodies: A Practical Approach, IRL Press (1988).

Various procedures known in the art may be used for the production of polyclonal antibodies to epitopes of a protein. For the production of polyclonal antibodies, a number of host animals are acceptable for the generation of antibodies by immunization with one or more injections of a polypeptide preparation, including but not limited to rabbits, mice, rats, etc. Various adjuvants may be used to increase the immunological response in the host animal, depending on the host species, including but not limited to Freund's (complete and incomplete), mineral gels such as aluminium hydroxide, surface active substances such as lysolecithin, pluronic polyols, polyanions, oil emulsions, keyhole lympet hemocyanins, dinitrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerin) and Corynebacterium parvum.

A monoclonal antibody to an epitope of a protein may be prepared by using any technique which provides for the production of antibody molecules by continuous cell lines in culture. These include but are not limited to the hybridoma technique originally described by Kohler and Milstein (1975, Nature 256, 493-497), and the more recent human B-cell hybridoma technique (Kesber et al. 1983, Immunology Today 4:72) and EBV-hybridoma technique (Cole et al. 1985, Monoclonal Antibodies and Cancer Therapy, Alan R. Liss, Inc. pp. 77-96). In addition, techniques developed for the production of “chimeric antibodies” by splicing the genes from antibody molecule of appropriate antigen specificity together with genes from a human antibody molecule of appropriate biological activity may be used (Morrison et al. 1984, Proc. Natl. Acad. Sci., 81:6851-6855; Neuberger et al. 1984 Nature 312:604-608; Takeda et al. 1985 Nature 31:452-454). Alternatively, techniques described for the production of single chain antibodies (U.S. Pat. No. 4,946,778) can be adapted to produce 4-specific single chain antibodies.

Recombinant human or humanized versions of monoclonal antibodies are a preferred embodiment for human therapeutic applications. Humanized antibodies may be prepared according to procedures in the literature (e.g. Jones et al. 1986, Nature 321:522-25; Reichman et al. 1988 Nature 332:323-27; Verhoeyen et al. 1988, Science 239:1534-36). The recently described “gene conversion metagenesis” strategy for the production of humanized monoclonal antibody may also be employed in the production of humanized antibodies (Carter et al. 1992 Proc. Natl. Acad. Sci. U.S.A. 89:4285-89). Alternatively, techniques for generating the recombinant phase library of random combinations of heavy and light regions may be used to prepare recombinant antibodies (e.g. Huse et al. 1989 Science 246:1275-81).

Antibody fragments which contain the idiotype of the molecule such as Fu F(ab1) and F(ab2) may be generated by known techniques. For example, such fragments include but are not limited to: the F(ab) E2 fragment which can be produced by pepsin digestion of the intact antibody molecule; the Fab′ fragments which can be generated by reducing the disulfide bridges of the F(ab′)2 fragment, and the two Fab fragments which can be generated by treating the antibody molecule with papain and a reducing agent. Alternatively, Fab expression libraries may be constructed (Huse et al. 1989, Science 246:1275-1281) to allow rapid and easy identification of monoclonal Fab fragment with the desired specificity to a protein.

Adjuvants

“Adjuvant” means a composition comprised of one or more substances that enhances the immunogenicity and efficacy of a vaccine composition. Non-limiting examples of suitable adjuvants include squalane and squalene (or other oils of animal origin); block copolymers; detergents such as Tween®-80; Quil® A, mineral oils such as Drakeol or Marcol, vegetable oils such as peanut oil; Corynebacterium-derived adjuvants such as Corynebacterium parvum; Propionibacterium-derived adjuvants such as Propionibacterium acne; Mycobacterium bovis (Bacillus Calmetic and Guerinn or BCG); interleukins such as interleukin 2 and interleukin-12; monokines such as interleukin 1; tumour necrosis factor; interferons such as gamma interferon; combinations such as saponin-aluminium hydroxide or Quil-A aluminium hydroxide; liposomes; ISCOM adjuvant; mycobacterial cell wall extract; synthetic glycopeptides such as muramyl dipeptides or other derivatives; Avridine; Lipid A; dextran sulfate; DEAE-Dextran or DHAE-Dextran with aluminium phosphate; carboxypolymethylene such as Carbopol EMA; acrylic copolymer emulsions such as Neocryl A640 (e.g. U.S. Pat. No. 5,047,238); vaccinia or animal posvirus proteins; sub-viral particle adjuvants such as cholera toxin, or mixtures thereof.

As used herein, stringent conditions are those that (1) employ low ionic strength and high temperature for washing, for example, 0.015 M NaCl/0.0015 M sodium citrate/0.1% NaDodSO4 at 50° C.; (2) employ during hybridisation a denaturing agent such as formamide, for example, 50% (vol/vol) formamide with 0.1% bovine serum albumin, 0.1% Ficoll, 0.1% polyvinylpyrrolidone, 50 mM sodium phosphate buffer at pH 6.5 with 750 mM NaCl, 75 mM sodium citrate at 42° C.; or (3) employ 50% formamide, 5×SSC (0.75 M NaCl, 0.075 M sodium citrate), 50 mM sodium phosphate (pH 6.8), 0.1% sodium pyrophosphate, 5×Denhardt's solution, sonicated salmon sperm DNA (50 μg/ml), 0.1% SDS and 10% dextran sulfate at 42° C. in 0.2×SSC and 0.1% SDS

As will be understood the present invention includes within its scope DNA vaccination. Further information regarding DNA vaccination may be found in Donnelly et al, Journal of Immunological Methods 176 (1994) 145-152, the disclosure of which is incorporated herein by reference.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element or integer or group of elements or integers but not the exclusion of any other element or integer, or group of elements or integers.

Preparation of the P. gingivalis Library for Sequencing.

To determine the DNA sequence of P. gingivalis genomic DNA was isolated from P. gingivalis strain W50 (ATCC 53978) essentially by the method described by Mamur J. (J. Mol. Biol. 3, 208-218, 1961). Cloning of DNA fragments was performed essentially as described by Fleischmann et al., (Science; 269, 496-512, 1995)(2). Briefly, purified genomic DNA from P. gingivalis was nebulized to fragment the DNA and was treated with Bal31 nuclease to create blunt ends then run twice through preparative 1% agarose gels. DNA fragments of 1.6-2.0 kb were excised from the gel and the DNA recovered. This DNA was then ligated to the vector pUC18 (SmaI digested and dephosphorylated; Pharmacia) and electrophoresed through a 1% preparative agarose gel. The fragment comprising linear vector plus one insert was excised, purified and this process repeated to reduce any vector without insert contamination. The recovered vector plus insert DNA was blunt-ended with T4 DNA polymerase, then a final ligation to produce circular DNA was performed. Aliquots of Epicurian Coli Electroporation-Competent Cells (Stratagene) were transformed with the ligated DNA and plated out on SOB agar antibiotic diffusion plates containing X-gal and incubated at 37° C. overnight. Colonies with inserts appeared white and those without inserts (vector alone) appeared blue. Plates were stored at 4° C. until the white clones were picked and expanded for the extraction of plasmid DNA for sequencing.

DNA Sequencing

Plasmid DNA was prepared by picking bacterial colonies into 1.5 ml of LB, TB or SOB broth supplemented with 50-100 ug/ml Ampicillin in 96 deep well plates. Plasmid DNA was isolated using the QIAprep Spin or QIAprep 96 Turbo miniprep kits (QIAGEN GmbH, Germany). DNA was eluted into a 96 well gridded array and stored at −20 C.

Sequencing reactions were performed using ABI PRISM Dye Terminator and ABI PRISM BIGDye Terminator Cycle Sequencing Ready Reaction kits with AmpliTaq DNA polymerase FS (PE Applied Biosystems, Foster City, Calif.) using the M13 Universal forward and reverse sequencing primers. Sequence reactions were conducted on either a Perkin-Elmer GeneAmp 9700 (PE Applied Biosystems) or Hybaid PCR Express (Hybaid, UK) thermal cyclers. Sequencing reactions were analysed on ABI PRISM 377 DNA sequencers (PE Applied Biosystems).

The sequences obtained are set out below. The relationship between these sequences is set out in Table 1. The initiation codon was calculated using a combination of sequence homology alignment (FASTA), signal sequence prediction (PSORT, SignalP) or ORF prediction (GeneMark).

TABLE 1 Reference table indicating the relationships of each sequence ID to the selected proteins. DNA sequence Amino acid of sequence of DNA Protein complete complete sequence of Amino acid name ORF ORF protein sequence of protein PG1 1 75 34 108 PG10 2 76 35 109 PG100 3 77 36 110 PG102 4 78 37, 38 111, 112 PG104 5 79 39 113 PG11 6 80 40 114 PG12 7 81 41 115 PG13 8 82 42 116 PG14 9 83 43 117 PG2 10 84 44, 45 118, 119 PG21 11 85 46 120 PG22 12 86 47 121 PG24 13 87 48 122 PG25 14 88 49 123 PG27 15 89 50 124 PG28 16 90 51 125 PG29 17 91 52 126 PG3 18 92 53 127 PG4 19 93 54 128 PG5 20 94 55 129 PG54 21 95 56 130 PG57 22 96 57, 58, 59 131, 132, 133 PG6 23 97 60 134 PG68 24 98 61, 62 135, 136 PG75 25 99 63 137 PG76 26 100 64 138 PG8 27 101 65, 66, 67, 68 139, 140, 141, 142 PG91 28 102 69 143 PG94 29 103 70 144 PG96 30 104 71 145 PG97 31 105 72 146 PG98 32 106 73 147 PG99 33 107 74 148 DNA Sequence Analysis

DNA files in FASTA format were converted to GCG format files and imported into a database. The DNA files were translated into amino acid files using the program Flip obtained from ANGIS (Australian Genomic Information Service, University of Sydney, Australia). A series of bioinformatic analyses were performed on the proteins in order to select potential vaccine candidates. The programs used were FASTA homology searching (1), PSORT (2,3), SignalP (4), TopPred (5), and GeneMark (6). The proteins and their bioinformatic results were stored in the custom written database for search and retrieval of proteins with the desired characteristics

The FASTA homology results for these proteins were then examined for any alignment with a protein suggesting surface location or vaccine efficacy. All proteins were searched for homology against a non-redundant bacterial protein database compiled by ANGIS using the FASTA algorithm. The settings used for the FASTA searches were Ktup=2, gap creation penalty=−12, gap extension penalty=−2, width for deriving alignment in opt=16 and the Blosum 50 scoring matrix. Individual FASTA search results were examined for significant homology by statistical probability and amino acid alignments. The results are set out in Table 2.

Protein files were then trimmed to the first, second, third, fourth and fifth methionine residues using a protein trimming program (ANGIS). The trimmed proteins were then subjected to PSORT analysis for the detection of signal sequences and the prediction of cell location. Proteins exhibiting a PSORT probability of outer membrane >0.8 were considered to indicate surface localisation. A second signal sequence detection program SignalP was also performed and, in certain instances, this program detected signals not identified with PSORT. All proteins identified by other methods were also analysed by PSORT and SignalP. Previously, the C-terminal amino acid of bacterial outer membrane proteins has been shown to be important for the assembly of the protein on the outer membrane (7). A typical structure definition for outer membrane proteins has been determined as the presence of a signal sequence at the N-terminus and a tyrosine or phenylalanine at the C-terminus. A number of the selected proteins exhibit this characteristic structure. The program TopPred was used to determine the presence and number of membrane spanning domains (MSDs) and the presence of such sequences indicates a preference to be attached to membranes such as the outer membrane. The results of PSORT, SignalP and TopPred analyses with the C-terminal amino acids of the selected proteins are set out in Table 3.

The 70 amino acids from the C-terminus of a number of P. gingivalis outer membrane proteins share 50-100% protein sequence identity. These proteins included RGP1, RGP2, KGP, HagA, HagC, HagD, prtH and prtT. This conserved motif may be involved in the attachment or sorting of proteins to the outer membrane. The protein data set was searched using FASTA homology as described above and a number of novel proteins were identified which demonstrate similar motifs at their C-termini. The results are listed in Table 4

The TonBIII box is a 30 amino acid motif present within TonB outer membrane receptors in a wide variety of bacteria. The TonBIII box of P. gingivalis (8) was used to search the protein data set for homology by FASTA as described above. Those proteins demonstrating significant homology are listed in Table 5.

TABLE 2 FASTA protein homology results of complete ORFs against a non-redundant protein database. Genbank Length of Protein accession Length of P. gingivalis FASTA homology results name Homology description number homolog protein Identity % Overlap E value PG1 48 kD outer membrane protein, Actinobacillus U24492  449aa  451aa 32  454aa 1.40E−42 pleuropneumoniae PG2 Outer membrane protein (susC), Bacteroides L49338 1038aa 1017aa, 28 1099aa 4.60E−32 thetaiotaomicron 1014aa PG3 Outer membrane porin F adhesin, Pseudomonas U19743  317aa  223aa 35  187aa 1.10E−10 fluorescens PG4 Outer membrane protein A, Escherichia fergusonii M63352  243aa  672aa 48  88aa 4.10E−10 PG5 Adhesin protein (AdcA), Streptococcus pneumoniae Z71552  423aa  315aa 25  279aa 9.40E−15 PG6 Hemolysin A (phyA), Prevotella melaninogenica U27587  332aa  324aa 60  306aa 3.00E−74 PG8 Heme uptake protein A, Bacteriodes fragilis X97122  431aa  598aa, 79  417aa 6.70E−121  550aa,  458aa,  426aa PG10 Macrophage infectivity potentiator (MIP), Legionella U92214  234aa  195aa 50  201aa 4.70E−31 oakridgensis. PG11 Haemagglutinin (phg), Prevotella intermedia AF017417  309aa  313aa 44  309aa 3.60E−44 PG12 Outer membrane lipoprotein, Haemophilus influenzae M68502  274aa  271aa 36  254aa 9.60E−27 PG13 Ferric receptor (cfrA), Campylobacter coli U80812  696aa  757aa 24  625aa 1.20E−18 PG14 36 kD antigen, Helicobacter pylori U86610  329aa  331aa 37  326aa 1.10E−35 PG22 Alpha-hemolysin gene, Aeromonas hydrophila L36462  85aa  106aa 57  67aa 2.60E−14 PG24 Putative hemolysin, Streptococcus mutans AF051356  445aa  417aa 29  432aa 1.80E−29 PG25 Cysteine protease, Porphyromonas gingivalis U54691 1723aa  293aa 42  142aa 1.10E−12 PG27 TonB linked adhesin, Porphyromonas gingivalis Y07618 1097aa  312aa 45  360aa 3.20E−41 PG28 Cysteine protease/hemagglutinin, Porphyromonas S75942  886aa  843aa 35  838aa 7.00E−90 gingivalis PG54 Protease I, Achromobacter lyticus J5128  653aa  940aa 24  695aa 1.50E−22 PG57 Cysteine protease, Porphyromonas gingivalis U68468 1358aa  924aa, 31  742aa 1.40E−23  922aa,  921aa PG75 Class 3 outer membrane porin (porB), Neisseria U07191  332aa  391aa 23  239aa 4.60E−01 meningitidis PG91 Neuraminidase (nanH), Bacteroides fragilis D28493  544aa  540aa 24  251aa 1.60E+00 PG94 Arginyl endopeptidase, Porphyromonas gingivalis D26470  991aa 1157aa 24  328aa 7.60E−08 PG21 Surface antigen gene, Methanosarcina mazei X84710  783aa  821aa 37  331aa 6.20E−33

TABLE 3 Results of PSORT, SignalP and TopPred analysis of the proteins. The signal present column indicates the presence of a signal sequence detected with either PSORT or SignalP. The terms in parentheses indicates the type of signal sequence as determined by PSORT. The cell location & probability values are generated by PSORT and represent the probability of the protein being in the cell compartments outer membrane (OM), inner membrane (IM), periplasmic space (PC) or cytoplasm (C). The number of transmembrane domains (TMDs) was determined by TopPred and does not include uncleavable signal sequences. Protein SignalP PSORT C-terminal Number Protein seqID Protein Methionine in cleavage cleavage Cell Location & probability Amino of name number Length Signal Present ORF site site OM IM PS C Acid TMD's PG1 386 451aa Y 1 24 34 0 0 0 0.22 N 0 PG2 424 1017aa  Y 1 20 20 0.94 0 0.33 0 F 3 PG2 425 1014aa  Y 2 17 17 0.94 0 0.29 0 F 3 PG3 434 223aa Y (lipoprotein) 1 — 18 0.79 0.76 0 0 K 3 PG4 447 672aa Y (lipoprotein) 1 22 22 0.79 0.7 0 0 R 0 PG5 458 315aa Y 1 40 35 0 0.25 0 0 R 0 PG6 475 324aa N 1 — — 0 0 0 0.2 S 1 PG8 498 598aa N 1 — — 0 0 0 0.22 N 0 PG8 499 550aa N 2 — — 0 0 0 0.25 N 0 PG8 500 458aa N 3 — — 0 0 0 0.34 N 0 PG8 501 426aa N 4 — — 0 0 0 0.24 N 0 PG10 387 195aa N 1 — — 0 0 0 0.11 K 0 PG11 400 313aa Y 1 22 26 0.24 0 0.93 0 R 1 PG12 411 271aa Y (lipoprotein) 3 27 29 0.79 0.7 0 0 R 0 PG13 419 757aa Y 1 23 25 0.94 0 0.29 0 N 0 PG14 420 331aa Y (uncleavable) 1 35 26 0 0.58 0 0 K 1 PG21 426 821aa Y 2 24 27 0.34 0 0.37 0 G 1 PG22 427 106aa Y (uncleavable) 1 41 41 0 0.29 0 0 P 0 PG24 429 417aa Y 1 19 19 0 0.44 0 0 N 3 PG25 430 293aa Y 1 27 28 0.2 0 0.62 0 R 0 PG27 431 312aa N 1 — — 0 0 0 0.28 Q 1 PG28 432 843aa Y 1 21 21 0.93 0 0.24 0 H 1 PG29 433 290aa Y 1 18 16 0.28 0 0.94 0 K 1 PG54 463 940aa Y 1 27 20 0.86 0 0.25 0 Q 5 PG57 467 925aa Y 1 28 24 0.53 0 0.2 0 P 3 PG57 468 922aa Y 2 25 21 0.53 0 0.2 0 P 3 PG57 469 921aa Y 3 24 20 0.53 0 0.2 0 P 3 PG68 484 1226aa  Y 1 25 25 0.91 0 0.31 0 Y 0 PG68 485 1225aa  Y 2 24 24 0.91 0 0.31 0 Y 0 PG75 493 391aa Y 1 26 26 0.94 0 0.3 0 H 1 PG76 494 446aa Y 1 21 22 0.94 0 0.32 0 V 3 PG91 520 540aa Y 1 25 25 0.85 0 0.30 0 E 0 PG94 523 1157aa  Y 1 23 28 0.8 0 0.25 0 Q 5 PG96 525 563aa Y 1 23 23 0.40 0 0.33 0 K 0 PG97 526 437aa Y 1 23 23 0.32 0 0.65 0 Q 0 PG98 527 318aa Y (lipoprotein) 1 19 19 0.79 0.7 0 0 L 1 PG99 528 461aa Y (uncleavable) 1 22 20 0 0 0.3 0 R 0 PG100 388 279aa Y 1 20 18 0.26 0 0.54 0 I 0 PG102 389 562aa Y 1 29 29 0.19 0 0.4 0 S 3 PG102 390 558aa Y 2 25 25 0.26 0 0.46 0 S 3 PG104 391 391aa Y 1 17 17 0.62 0 0.22 R 0

TABLE 4 Percentage identity and percentage similarity of various proteins with the 70 amino acids from the C-terminal of the P. gingivalis arginine protease 1 (RGP1), arginine protease 2 (RGP2), and the cysteine protease/hemagglutinin (prtT). Protein Percent identity Percent similarity name RGP1 RGP2 prtT RGP1 RGP2 prtT PG21 17 29 21 40 57 49 PG25 43 41 9 64 73 14 PG27 41 33 7 73 74 11 PG28 21 26 34 49 57 74 PG54 19 13 16 40 43 33 PG57 11 14 19 20 24 34 PG91 31 21 39 57 53 74 PG96 0 13 20 0 24 43 PG97 10 26 33 14 47 61 PG98 16 20 0 47 54 0 PG99 19 0 26 41 0 54 PG100 20 21 24 39 57 41 PG102 27 20 31 50 61 61 PG104 16 23 26 46 44 49

TABLE 5 Percentage identity and percentage similarity of various proteins with the TonBIII box of P. gingivalis. Protein name Percent identity Percent similarity PG2 46 71 PG13 57 93 Cloning, Expression and Purification of Recombinant P. gingivalis Genes. PG1

Oligonucleotides to the 5′ and 3′ regions of the deduced protein were used to amplify the gene of interest from a preparation of P. gingivalis W50 genomic DNA using the TaqPlus Precision PCR System (Stratagene) and a PTC-100 (MJ Research) thermal cycler or similar device. The 5′ oligonucleotide primer sequence was GCGCCATATGCTGGCCGAACCGGCC (SEQ ID NO: 149) the 3′ oligonucleotide primer sequence was GCGCCTCGAGTCAATTCATTTCCTTATAGAG (SEQ ID NO: 150). The PCR fragment was purified, digested with Nde I, Xho I restriction enzymes (Promega) and ligated into the corresponding sites of the plasmid pProEx-1 (Gibco-BRL) and transformed into E. coli ER1793 cells (a gift from Elizabeth Raleigh, New England Biolabs). A resulting clone expressing the correct insert was selected and induced with or without 0.1 mM IPTG (Promega) for expression of the recombinant protein. Expression of the recombinant protein was determined by SDS-PAGE analysis and Western Blot using the one of the rabbit antisera described above or an anti-hexahistidine antibody (Clontech) that detects the hexahistidine tag that was fused to the P. gingivalis recombinant protein. PG1 was purified by disruption of the E. coli cells by sonication in binding buffer (Novagen) and solubilisation by the addition of sarkosyl (N-Lauroyl sarcosine) to a 1% final concentration. There after the preparation was diluted to 0.1% sarkosyl in binding buffer, bound to a Nickel-nitrilotriacetic acid column (Ni-NTA; Qiagen), after washing bound proteins were eluted with 1M imidazole in elution buffer (Novagen) according to the Qiagen recommendations with 0.1% sarkosyl added to all buffers. Following purification samples were dialysed against 500 mM NaCl, 20 mM Tris, 0.1% sarkosyl at pH7.4 to remove the imidazole, concentrated as required and stored at 4° C. until used. Purity and antigenicity were assessed by SDS-PAGE and Western blot using selected antisera (from those described above) and the protein concentration was determined by the BCA assay (Pierce).

PG2

The methods used for PG2 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGGTATACATGAAAAGAATGACGC (SEQ ID NO: 151), the 3′ oligonucleotide primer sequence was CGCGAGATCTGAAAGACAACTGAATACC (SEQ ID NO: 152) and the PCR product was cloned into pGex-stop RBS(IV) (Patent application WO9619496, J C Cox, S E Edwards, I Frazer and E A Webb. Variants of human papilloma virus antigens) using the BstZ 171 and Bgl II restriction sites. 2% sarkosyl was used to solubilise PG2 and 8M urea was added to the solublisation buffer and to all other buffers. Urea was removed from the purified protein by sequential dialysis (4M then 2M then 1M then 0.5M then 0M urea all in 50 mM Tris, 500 mM NaCl, 0.1% sarkosyl, pH7.4). Purified protein was stored at 4° C. until required.

PG3

The methods used for PG3 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCGTATACATGAAGAAATCAAGTGTAG (SEQ ID NO: 153), the 3′ oligonucleotide primer sequence was GCGCAGATCTCTTCAGCGTACCTTGCTGTG (SEQ ID NO: 154) and DNA was amplified with Pfu DNA polymerase (Stratagene). The PCR product was cloned directly into pCR-Blunt and transformed into E. coli Top 10F′ (InVitrogen) before subcloning into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli BL21DE3 (Pharmacia Biotech). The following modifications were made to the purification of PG3 from the PG1 method. Cells expressing the recombinant protein were disrupted by sonication in binding buffer and the insoluble inclusion bodies concentrated by centrifugation. Inclusion bodies were then solubilised in 6M urea (Sigma) in binding buffer and eluted with 6M urea added to the elution buffer. In some instances 6M guanidine hydrochloride (Sigma) was used instead of urea for these steps. Urea (or guanidine hydrochloride when it was substituted) was removed from the purified protein by sequential dialysis against reducing levels of urea (3M then 1.5M then 0.5M then 0M urea all in 50 mM Tris, 500 mM NaCl, 8% glycerol, pH7.4). Purified protein was stored frozen at −80° C. until required. Protein concentration was determined by the Coomassie Plus protein assay (Pierce).

PG4

The methods used for PG4 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CTTCTGTATACTTACAGCGGACATCATAAAATC (SEQ ID NO:155), the 3′ oligonucleotide primer sequence was TTCCAGGAGGGTACCACGCAACTCTTCTTCGAT (SEQ ID NO: 156) and DNA was amplified with the Tth XL PCR kit (Perkin Elmer). The PCR product was cloned into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Kpn I restriction sites and transformed into E. coli ER1793.

PG5

The methods used for PG5 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was TTGCAACATATGATCAGAACGATACTTTCA (SEQ ID NO: 157) the 3′ oligonucleotide primer sequence was AGCAATCTCGAGCGGTTCATGAGCCAAAGC (SEQ ID NO: 158) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24 (Novagen) using the Nde I and Xho I restriction sites and transformed into E. coli BL21 (Pharmacia Biotech). Removal of urea was not proceeded past 1M urea as the protein was insoluble at lower concentrations of urea. Purified protein was stored at 4° C. until required.

PG6

The methods used for PG6 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was TAAACATATGTCCCTCGAACCCATAATTGCTCCG (SEQ ID NO:159), the 3′ oligonucleotide primer sequence was CGTCCGCGGAAGCTTTGATCGGCCATTGCTACT (SEQ ID NO: 160) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Nde I and Hind III restriction sites and transformed into E. coli BL21.

PG8

The methods used for PG8 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGGTATACATGGAGTTCAAGATTGTG (SEQ ID NO:161), the 3′ oligonucleotide primer sequence was CGCGAGATCTGTTTTCTGAAAGCTTTTC (SEQ ID NO: 162) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was cloned into the expression plasmid pProEx-1 using the Nde I and Xho I restriction sites and transformed into E. coli ER1793.

PG8A

PG8A is a shortened version of PG8 and has the first 173 amino acids removed. The methods used for PG8A were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGGTATACATGGAAAACTTAAAGAAC (SEQ ID NO:163), the 3′ oligonucleotide primer sequence was CGCGAGATCTGTTTTCTGAAAGCTTTTC (SEQ ID NO: 164) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was cloned into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli ER1793. Prior to dialysis of the purified protein EDTA (Sigma) was added to a final concentration of 10 mM.

PG10

The methods used for PG10 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGGATATCATGGATAAAGTGAGCTATGC (SEQ ID NO:165), the 3′ oligonucleotide primer sequence was CGCGAGATCTTTTGTTGATACTCAATAATTC (SEQ ID NO: 166) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was digested with Eco RV and Bgl II and ligated into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli ER1793.

PG11

The methods used for PG11 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCGTATACATGAGAGCAAACATTTGGCAGATACTTTCCG (SEQ ID NO: 167), the 3′ oligonucleotide primer sequence was GCGCAGATCTGCGCAAGCGCAGTATATCGCC (SEQ ID NO: 168) and DNA was amplified with Tli DNA polymerase (Promega). The PCR product was cloned into pCR-Blunt and transformed into E. coli Top10F′ before subcloning into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli ER1793. PG11 was purified by solubilisation of E. coli cells with 2% sarkosyl in binding buffer (Qiagen) which was diluted to 0.1% sarkosyl in binding buffer, bound to a Nickel-nitrilotriacetic acid column (Ni-NTA; Qiagen), after washing bound proteins were eluted with 1M imidazole (0.7% CHAPS (Sigma) in elution buffer; Qiagen) according to the Qiagen recommendations. Following purification samples were dialysed against 500 mM NaCl, 20 mM Tris, 0.7% CHAPS, 20% glycerol (Sigma) at pH7.4 to remove the imidazole, concentrated as required and stored at 4° C. until used.

PG12

The methods used for PG12 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCGTATACATGAATAGCAGACATCTGACAATCACAATCATTGCCGG (SEQ ID NO: 169), the 3′ oligonucleotide primer sequence was GCGCAGATCTGCTGTTCTGTGAGTGCAGTTGTTTAAGTG (SEQ ID NO: 170) and DNA was amplified with Tli DNA polymerase. The PCR product was cloned into pCR-Blunt and transformed into E. coli Top10F′ cells before subcloning into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli BL21. Purification of the recombinant protein was essentially the same as PG11 except 0.5% DHPC (1,2-Diheptanoyl-sn-glycero-3-phosphocholine; Avanti) in 50 mM Tris, 50 mM NaCl, pH8.0 was used to solubilise the inclusion bodies instead of sarkosyl and the DHPC was diluted to 0.1% before addition to the Ni-NTA and 0.1% DHPC was added to all buffers.

PG13

The methods used for PG13 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCCATATGCGGACAAAAACTATCTTTTTTGCG (SEQ ID NO:171), the 3′ oligonucleotide primer sequence was GCGCCTCGAGGTTGTTGAATCGAATCGCTATTTGAGC (SEQ ID NO: 172) and DNA was amplified with Tli DNA polymerase. The PCR product was cloned the expression plasmid pET24b using the Nde I and Xho I restriction sites and transformed into E. coli BL21. Purification of the recombinant protein was essentially the same as PG3 using 6M urea and 1% NOG (n-octyl glucoside; Sigma) was added to the dialysis buffer. Removal of urea was not proceeded past 2M urea as the protein was insoluble at lower concentrations of urea. Purified protein was stored at 4° C. until required.

PG14

The methods used for PG12 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCGGCGCCATGACGGACAACAAACAACGTAATATCG (SEQ ID NO: 173), the 3′ oligonucleotide primer sequence was GCGCCTCGAGTTACTTACGTATGATCACGGACATACCC (SEQ ID NO: 174) and DNA was amplified with Tli DNA polymerase. The PCR product was cloned the expression plasmid pProEx-1 using the Ehe I and Xho I restriction sites and transformed into E. coli BL21. Purification of the recombinant protein was essentially the same as PG12.

PG22

The methods used for PG22 were essentially the same as for PG1 with the following exceptions. The 5′ oligonucleotide primer sequence was CCCCGGATCCGATGCGACTGATCAAGGC (SEQ ID NO:175), the 3′ oligonucleotide primer sequence was CCCCCTCGAGCGGAACGGGGTCATAGCC (SEQ ID NO: 176) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was cloned into the expression plasmid pET24b using the Bam HI and Xho I restriction sites and transformed into E. coli BL21DE3. Once PG22 was purified dialysis was performed in the same manner as for PG1 but in the presence of 1M imidazole.

PG24

The methods used for PG24 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGGTATACATGAATTACCTGTACATAC (SEQ ID NO: 177), the 3′ oligonucleotide primer sequence was CGCGGGATCCGTTCGATTGGTCGTCGATGG (SEQ ID NO: 178) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was digested with Bst Z171 and Bam HI and ligated into the expression plasmid pGex-stop RBS(IV) using the Bst Z171 and Bgl II restriction sites and transformed into E. coli ER1793. Due to the low level of expression of PG24 purification was not proceeded with except on small scale.

PG24A

A modified version of PG24 was also cloned and expressed. PG24A is the same as PG24 with the predicted N-terminal sequence removed. The methods used for PG24A were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was CGCGCATATGGAGATTGCTTTCCTTTCTTCG (SEQ ID NO: 179), the 3′ oligonucleotide primer sequence was CGCGCTCGAGTTAGTTCGATTGGTCGTCG (SEQ ID NO: 180) and DNA was amplified with the TaqPlus Precision PCR System. The PCR product was cloned into the expression plasmid pProEx-1 using the Nde I and Xho I restriction sites and transformed into E. coli ER1793. Purification of the recombinant protein was essentially the same as PG3 except 8M urea was used to solubilise the inclusion bodies and in the buffers used for the Ni-NTA column purification. Urea was removed by sequential dialysis (4M then 2M, then 1M then 0.5M then 0M urea all in 50 mM Tris, 500 mM NaCl, 8% glycerol, pH7.4). Purified protein was stored frozen at −80° C. until required.

PG29

The methods used for PG29 were essentially the same as for PG3 with the following exceptions. The 5′ oligonucleotide primer sequence was GCGCGATATCGCTAGCATGAAAAAGCTATTTCTC (SEQ ID NO: 181), the 3′ oligonucleotide primer sequence was GCGCAGATCTCTCGAGTTTGCCATCGGATTGCGGATTG (SEQ ID NO: 182) and DNA was amplified with Pfu DNA polymerase being used. The PCR product was cloned into pCR-Blunt (InVitrogen) and transformed into E. coli Top10F′ before subcloning into the expression plasmid pGex-stop RBS(IV) using the EcoR V and Bgl II restriction sites and transformed into E. coli BL21. 6M urea was used throughout the purification process.

PG54

The methods used for PG54 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was CGCTGAATTCCAGATTTCGTTCGGAGGGGAACCC (SEQ ID NO: 183), the 3′ oligonucleotide primer sequence was CTATGCGGCCGCCTGCTTCACGATCTTTTGGCTCA (SEQ ID NO: 184) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG57

The methods used for PG57 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was TGCTGGATCCCAAGAGATCTCAGGCATGAATGCA (SEQ ID NO: 185), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTCGGCCTCTTTATCTCTACCTTTTC (SEQ ID NO: 186) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Bam HI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG68

The methods used for PG68 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GCTTGCGGCCGCCCTTATGAAAGATTTGCAGAT (SEQ ID NO: 187), the 3′ oligonucleotide primer sequence was GGTGCTCGAGTATACTCAACAAGCACCTTATGCAC (SEQ ID NO: 188) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Not I and Xho I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG75

The methods used for PG75 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GGCGGGATCCGCTCAGGAGCAACTGAATGTGGTA (SEQ ID NO: 189), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTGTGGAACAAATTGCGCAATCCATC (SEQ ID NO: 190) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Bam HI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG76

The methods used for PG76 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was AGCAGAATTCGGAAACGCACAGAGCTTTTGGGAA (SEQ ID NO: 191), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTACCTGCACCTTATGACTGAATAC (SEQ ID NO: 192) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG91

The methods used for PG91 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was TGCTGAATTCCAGACGATGGGAGGAGATGATGTC (SEQ ID NO: 193), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTTCCACGATGAGCTTCTCTACGAA (SEQ ID NO: 194) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG94

The methods used for PG94 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GGCCGAGCTCCAAGAGGAAGGTATTTGGAATACC (SEQ ID NO: 195), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTTGTCCTACCACGATCATTTTCTT (SEQ ID NO: 196) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG96

The methods used for PG96 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was TGCTGAGCTCCAAACGCAAATGCAAGCAGACCGA (SEQ ID NO: 197), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTTTGAGAATTTTCATTGTCTCACG (SEQ ID NO: 198) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Sac I and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG97

The methods used for PG97 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GGCGGGATCCCAGTTTGTTCCGGCTCCCACCACA (SEQ ID NO: 199), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTCTGTTTGATGAGCTTAGTGGTATA (SEQ ID NO: 200) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Bam HI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG98

The methods used for PG98 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was AGCAGAATTCCAAGAAAGAGTCGATGAAAAAGTA (SEQ ID NO: 201), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTAGCTGTGTAACATTAAGTTTTTTATTGAT (SEQ ID NO: 202) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG99

The methods used for PG99 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was TGCTGAATTCAAGGACAATTCTTCTTACAAACCT (SEQ ID NO: 203), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTCGAATCACGACTTTTCTCACAAA (SEQ ID NO: 204) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG100

The methods used for PG100 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GGCAGAATTCCAGTCTTTGAGCACAATCAAAGTA (SEQ ID NO: 205), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTGATAGCCAGCTTGATGCTCTTAGC (SEQ ID NO: 206) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG102

The methods used for PG102 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GGCCGAATTCCAGATGGATATTGGTGGAGACGAT (SEQ ID NO: 207), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTCTCTACAATGATTTTTTCCACGAA (SEQ ID NO: 208) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Eco RI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

PG104

The methods used for PG104 were essentially the same as for PG3 with the following exceptions. The predicted N-terminal signal sequence was removed from the recombinant protein. The 5′ oligonucleotide primer sequence was GAACGGATCCAACGTGTCTGCTCAGTCACCCCGA (SEQ ID NO: 209), the 3′ oligonucleotide primer sequence was GAGTGCGGCCGCTTCTGAGCGATACTTTTGCACGTAT (SEQ ID NO: 210) and DNA was amplified with the Tth XL PCR kit. The PCR product was cloned into the expression plasmid pET24a using the Bam HI and Not I restriction sites and transformed into E. coli BL21DE3. Expression studies and immunoreactivity studies were carried out on whole E. coli lysates. Purification was not done for these studies.

Animal Antisera and Human Patient Sera.

Various antisera were raised for detecting the expression and refolding of the recombinant P. gingivalis proteins. A whole cell antisera was raised by injecting New Zealand White rabbits with 3 doses of sonicated P. gingivalis (strain W50) containing approximately 2 mg of protein. The first dose was given in Freunds complete adjuvant (FCA) and the second and third doses were given in Freunds incomplete adjuvant (IFA) at 3 week intervals. Doses (1 ml) were given intramuscularly into the hind legs and rabbits bled 7 days after the last dose, the blood clotted and serum removed and stored at −20° C. until required. A second rabbit antisera was produced in a similar manner but using a sarkosyl insoluble fraction (each dose was 0.69 mg of protein) derived from P. gingivalis W50 according to the method of Doidg and Trust T. et al 1994 as the immunogen. A third rabbit antisera was produced in a similar manner to the first only the sarkosyl soluble fraction (1 mg of protein per dose) derived from P. gingivalis W50 cells according to the method of Doidg P. and Trust T J. (1994 Infect Immun 62:4526-33) was used as the immunogen.

A “protected rat serum” pool was also used in these studies and was obtained from rats immunised with formalin killed whole P. gingivalis cells in FIA (strain ATCC 33277; 2 doses of 2×10⁹ cells, 3 weeks apart). Rats were then challenged 2 weeks after their last dose with live P. gingivalis cells (strain 33277) given orally as previously described (Klaussen B. et al. 1991, Oral Microbiol Immunol 6:193-201) and the serum obtained from these rats 6 weeks after the final challenge inoculation at the time of sacrifice.

Human sera were obtained from adult patients undergoing treatment or assessment for periodontitis at an outpatient clinic. These patients had at least 6 teeth with 6 mm attachment loss and had P. gingivalis present in their sub-gingival plaque as detected using a P. gingivalis specific DNA probe. Sera was pooled from these patients and compared to a pool of sera from periodontally healthy patients.

Immunization and Murine Lesion Model Protocols

The mouse abscess model was used to assess the efficacy of immunising mice with recombinant P. gingivalis proteins in protecting mice from formation of a subcutaneous abscess. This model has been used by others as a predictor of potential vaccines against periodontal disease (Bird P S, et al. 1995 J. Periodontal. 66:351-362. BALB/c mice 6-8 weeks old were immunised by subcutaneously injecting them with 0.1 ml containing either 10 or 20 μg of recombinant P. gingivalis protein, 20 μg of E. coli lysate protein, 2×10⁹ formalin killed cells of P. gingivalis strain 33277 emulsified in incomplete Freund's adjuvant (WA; Sigma) on day 0. At day 21 mice were re-injected with the same dose and then bled 1 week later and evaluated for antibody levels. At day 35 mice all mice were challenged with approximately 2×10⁹ cells of live P. gingivalis (ATCC 33277) by subcutaneous injection in the abdomen. Following challenge mice were monitored daily for weight loss and the size of the lesion measured for the next 10 days. Lesion sizes were measured by length and width and expressed as mm². Groups were statistically analysed using a Kruskal-Wallis one-way ANOVA and were also individually examined using the unpaired t test or Mann-Whitney rank sum test using the Instat statistical package.

FIG. 1 shows the results of one experiment at day 4 after challenge (lesions were at maximum size at this time point). Control mice immunised with E. coli lysate showed large lesions while mice immunised with killed cells of P. gingivalis strain 33277 were fully protected. This indicates that whole cells provide protection against P. gingivalis while E. coli protein immunised mice were not protected. Mice given the various PG recombinant proteins showed significant levels of protection for PG2, PG22, PG24 and PG29 (p<0.05 unpaired t test) while PG8A was not quite significantly different (p=0.07) compared to the E. coli control group.

FIG. 2 shows the results of a separate experiment using combinations of recombinant proteins. Mice given PG1+PG2 showed a significant level of protection compared to control mice give E. coli lysate (p<0.026 unpaired t test).

IMMUNOSCREENING

Cloned candidates were cultured in 15 ml of Terrific broth, induced with IPTG and sampled at 4 h post-induction. One ml of culture was removed, pelleted and the cells resuspended in a volume of PBS determined by dividing the OD A_(600 nm) of the culture by 8. An aliquot of lysate (100 μl) was added to 100 μl of 2× sample reducing buffer (125 mM Tris pH 6.8, 20% glycerol, 4% SDS, 80 mM DTT, 0.03% bromophenol blue) and boiled for 10 min. SDS-PAGE was performed according to the method of Laemmli UK. 1970 (Nature 227:680-685) using 4-20% 1.0 mm Tris-Glycine gels (Novex) according to the manufacturers recommendations. Proteins were transferred onto Hybond-C Extra nitrocellulose membranes (Amersham) by transblotting and the membranes were then blocked for 2 h at room temperature (RT) in 5% skim milk in 20 mM Tris, 0.5M NaCl, 0.05% Tween-20, pH 7.5 (TTBS).

Immunoscreening was performed separately with the rabbit anti-P. gingivalis whole cell serum, the rat protective serum, a pool of human periodontal patients serum, and in many cases an anti-T7-Tag antibody HRP conjugate (Novagen). Prior to use, the rabbit, rat and human sera were diluted 1/5000, 1/1000 and 1/500 respectively in 5% skim milk in TTBS and absorbed with 100 μl (for the rabbit serum) or 250 μl (for the rat and human sera) E. coli extract (20 mg/ml; Promega) for 6 h at RT.

Membranes were incubated overnight at RT with the absorbed antisera, or for 1 hr at RT with 1/5000 diluted anti-T7-Tag conjugate. Following 3×10 min washes with TTBS, HRP-conjugated anti-rabbit (Silenus), anti-mouse (Silenus) or anti-human (KPL) antibody, diluted 1/5000 in 5% skim milk in TTBS, was added for 1 h at RT. Membranes were washed as before, prior to addition of TMB membrane peroxidase substrate (KPL) for detection of immunoreactive proteins. Results of reactivity for the recombinant P. gingivalis proteins is shown in Table 7.

In addition some of the sera (pooled sera diluted 1/1000) from the mice immunised with P. gingivalis recombinant proteins (prior to challenge) were analysed for their reactivity against Western blots of whole native W50 P. gingivalis proteins using similar techniques as those outlined above. PG2, PG8A, PG29 and PG3 all showed bands at a similar molecular weight to that of the recombinant PG protein in the native W50 blot. This indicates that PG proteins are expressed in the W50 strain and that the recombinant proteins have at least some identical immunogenicity to the native proteins.

m-RNA Analysis

Hot Phenol RNA Extraction

P. gingivalis W50 cells (150 ml culture) were grown anaerobically to mid log phase (OD A₆₀₀=0.18) mixed with 50% glycerol and stored at −70° C. until RNA extraction. Cells were pelleted by centrifugation at 6000 g, and resuspended in 8 ml ASE (20 mM NaOAc, 0.5% SDS, 1 mM EDTA). An equal volume of 20 mM NaOAc(pH 4.5)-saturated phenol was added and mixed by shaking for 30 seconds, incubated at 65° C. for 5 minutes, followed by a further 5 second shaking and repeated incubation. After cooling, 2 ml chloroform was added and mixed by shaking for 5 seconds, and the mixture spun at 10000 g for 10 minutes at 4° C. The top aqueous phase was transferred and re-extracted by repeating the phenol and chloroform steps. The aqueous phase was transferred again and 100 U RNase inhibitor (RNAsin; Promega) were added. RNA was precipitated with 3 volumes 100% ethanol at −20° C. overnight. The RNA precipitate was recovered by centrifugation at 10000 g at 4° C. for 15 minutes, then washed with 100% ethanol, dried and resuspended in 600 μl sterile, deionised, dH₂O with 1 μl of fresh RNase inhibitor. RNA was aliquoted and stored at −70° C. The RNA concentration was determined spectrophotometrically. A formaldehyde RNA gel confirmed RNA integrity (Sambrook J. et al. 1989, Molecular Cloning. A laboratory manual. Cold Spring Laboratory Press, New York. 2nd Edition).

RT-PCR

The isolated RNA was used as a template for Reverse Transcription (RT) to produce cDNA. Varying RNA concentrations were used for the RT as each RNA transcript was potentially present at different levels. Subsequent amplification of the cDNA was performed using Polymerase Chain Reaction (PCR). RT-PCR was performed using GeneAmp® RNA PCR Kit (Perkin Elmer) according to the manufacturer's protocol with the following exception to the PCR; 35 cycles were performed as follows: Melt phase 95° C. for 30 seconds, Anneal phase varied between 50-60° C. for 30 seconds, Extension phase 72° C. for 1 minute. Amplification was performed in a PTC-100 Programmable Thermal Controller (MJ Research Inc.). As a control to demonstrate that the amplified product did not arise from contaminating DNA, Reverse Transcriptase (RTase) was omitted from a parallel tube. The PCR products were examined against DNA markers (GIBCO 1 kB ladder) on a 1% agarose gel stained with ethidium bromide.

RT-PCR results are shown in Table 6 using the oligonucleotide primers as used in “Cloning, expression and purification of recombinant P. gingivalis genes” section described above, except for the following changes. For PG1 the 3′ reverse primer used was GCGCCTCGAGATTCATTTCCTTATAGAG (SEQ ID NO: 211), for PG4 the 5′ forward primer was CTTCTTGTCGACTACAGCGGACATCATAAAATC (SEQ ID NO: 212) and the 3′ reverse primer was TTCCACCTCGAGTTAACGCAACTCTTCTTCGAT (SEQ ID NO: 213), for PG6 the 5′ forward primer was TAAAGAATTCTGCCTCGAACCCATAATTGCTCCG (SEQ ID NO: 214), for PG10 the 5′ forward primer was CGCGCATATGGATAAAGTGAGCTATGC (SEQ ID NO: 215) and the 3′ reverse primer was CGCGCTCGAGTTTGTTGATACTCAATAATTC (SEQ ID NO: 216), for PG13 the 5′ forward primer was GCCCGGCGCCATGCGGACAAAAACTATCTTTTTTGCG (SEQ ID NO: 217) and the 3′ reverse primer was GCCCGGCGCCTTAGTTGTTGAATCGAATCGCTATTTGAGC (SEQ ID NO: 218). Amplification of P. gingivalis transcripts is a likely indication that RNA for a specific candidate is present and that the protein is produced. However, where there is no amplification achieved this does not indicate that this gene is never transcribed and may be the result of the culture conditions or the state of the cells when harvested.

TABLE 6 Expression of PG m-RNA with in vitro grown P. gingivalis W50. The symbols are + band visible on agarose gel, − no band present on agarose gel, ND not detected. Approx. Expected RNA Annealing PCR fragment fragment PG # μg temp. ° C. RT-PCR (-RT) size bp size bp  1 0.15 55 + − 1300 1362  2 1.0 50 + − 3200 3051  3 0.15 60 + − 720 690  4 2.9 55 − − N.D. 2000  5 0.02 50 + − 1000 947  6 1.0 55 + − 1000 972  8A 0.15 50 + − 1200 1278 10 0.15 55 + − 590 585 11 0.10 60 + − 960 942 12 0.02 60 + − 880 831 13 1.0 50 + − 2150 2274 14 0.15 60 + − 1050 996 22 1.0 60 − − N.D. 228 24 1.0 55 + + 1150 1194 29 0.15 60 + − 880 885

TABLE 7 Immunoblot results of proteins expressed in E. coli against rabbit, rat and human antisera. Deduced MW was calculated from amino acid sequence of the P. gingivalis proteins, some of which had their N-terminal signal sequences removed. Apparent MW was determined from SDS-PAGE gels. The N- and C-terminal tags add approximately 2.5 KDa to the deduced MW of the recombinant proteins. The symbols are + positive, − negative, +/− weak positive, ND not done. Protein Deduced MW Apparent Antisera reactivity number (KDa) MW (KDa) T7 Rabbit Rat Human PG1 47.5 63 ND − − − PG2 112.4 125.7 ND + − − PG3 22.6 18.3 ND −^(a) − − PG4 75 90.6 ND − − − PG5 34.9 43.8 ND − − − PG6 36.7 47.1 ND − − − PG8 67.5 63.1 ND −^(b) − − PG8A 47.7 90.6 ND − − − PG10 21.3 25.5 ND + − + PG11 36.2 42.4 ND − − − PG12 30.7 30.6 ND − − − PG13 84.5 101 ND − − − PG14 36 42.4 ND − + + PG22 8.6 11.1 ND − − − PG24A 47 63.1 ND − − − PG29 31.1 40.9 ND + + + PG54 101.4 46.7 + + − − PG57 100 134.5 + + + + PG68 133.3 30.7 + − + + PG75 40.7 46.7 + − − − PG76 48.1 55.6 + − − + PG91 57.2 85.7 + + + + PG96 59.3 70.3 + + + + PG97 44.4 57.5 + − + + PG98 33.3 36 + − − − PG99 40.7 55.6 + − + + PG100 29.6 10.8 + − − − PG102 59.3 70.3 + − − + PG104 40.7 57.5 + − − + ^(a)Positive reaction detected with the rabbit antiserum to sarkosyl insoluble P. gingivalis antigen. ^(b)Purified protein demonstrated weak positive reaction with the rabbit antiserum to whole P. gingivalis.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

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The invention claimed is:
 1. An isolated antigenic Porphyromonas gingivalis polypeptide comprising the amino acid sequence of SEQ ID NO:146.
 2. An immunogenic composition directed against P. gingivalis, comprising an amount of the polypeptide of claim 1 effective to induce an immune response against P. gingivalis and a pharmaceutically acceptable carrier.
 3. The composition as claimed in claim 2, wherein the pharmaceutically acceptable carrier comprises an adjuvant. 